A very simple battery charger circuit having reverse polarity indication is shown here.The circuit is based on IC L200 . L200 is a five pin variable voltage voltage regulator IC.The charging circuit can be fed by the DC voltage from a bridge rectifier or center tapped rectifier.Here the IC L200 keeps the charging voltage constant.The charging current is controlled by the parallel combination of the resistors R2 & R3.The POT P1 can be used to adjust the charging current.This circuit is designed to charge a 12 V lead acid battery.The transistor t1,diode D3 and LED are used to make a battery reverse indicator.In case the battery is connected in reverse polarity ,the reverse polarity indicator red LED D5 glows.When the charging process is going on the battery charging indicator green LED D4 glows.

Circuit diagram with Parts list.

Notes.

The circuit can be assembled on a good quality PCB or common board.

The values of R2 & R3 can be obtained from the equation,

(R2//R3) =( V5-2)/(Io).

Where V5 is the charging voltage (voltage at pin 5) and Io is the charging current.

Hi sir, may i ask how much input voltage do i require to charge a 12V 1.2ah battery? and any modification i need to make in this circuit ?
It means when the battery is not charging, the red LED light will light up? and green will light up once there’s supply voltage to charge the battery?

Hi Favour you require 15 volt 20Amps charger. you can use the following circuit with suitable pass transistors to increase current capacity to 20amps. do not forget to replace the transformer with 20 amps capacity.

I would like to resurrect an old charge car batteries and provide it with a new charging circuit.
I wanted to know if at this circuit you can add a few transistors (eg 2N3055) to increase the charge current.
I wanted to know if the battery is charged when the circuit stops charging.

I would use the existing transformers, I added a bridge rectifier diode and a capacitor 6.8 mF and I measured in the output 21VCC
If someone is kind enough to send me some simple automatic battery charger and stabilized.
Greetings
Thanks

Hi Paul the limitation for L200 is 2amps. you can use any PNP power transistor similar to, increasing current capability of 3pin regulators. please refer to national applicationhttp://www.national.com/an/AN/AN-103.pdf

I would like to resurrect an old charge car batteries and provide it with a new charging circuit.
I wanted to know if at this circuit you can add a few transistors (eg 2N3055) to increase the charge current.
I wanted to know if the battery is charged when the circuit stops charging.
If you have any simple battery charging circuit stabilized and can automatically send it to me
Greetings
Thanks

Hi Holly V5 and Io depends on the battery you want to charge. it depends on its terminal voltage and AH capacity. R2 & R3 are in parallel enable you to make the required value by using standard preferred values.